The present invention relates to a new process for the preparation of new chlorinated imidazole derivates and to a process for their preparation. The compounds of the invention can be used as intermediate products for the synthesis of plant protection agents, e.g. herbicides.
It is already known that polybrominated imidazole derivatives, for example 2,4,5-tribromoimidazole, are obtained if imidazole is brominated in ether or chloroform (G. Wyss, Ber. dtsch. chem. Ges. 10, 1365 (1877); J. E. Balaban and F. L. Pyman, J. Chem. Soc. [London] 121, 947 (1922); K. Hofman in: The Chemistry of Heterocyclic Compounds, A. Weissberger Editor, Interscience Publishers, Inc. New York, Vol. 6, page 111 et seq.). The corresponding trichloroimidazole cannot be prepared in this way.
Furthermore it is known that 2,4,5-trichloroimidazole is obtained by heating 2,4,5-tribromoimidazole with concentrated hydrochloric acid (J. Heterocycl. Chem., 399 - 402 (1967)).
It has not hitherto been possible to synthesise other chlorinated imidazole derivatives. Various attempts to arrive at usable results by varying the methods of chlorination, such as, for example, by using chlorine in the presence of FeCl.sub.3, by photochlorination, by using chlorine in the presence of sodium hydroxide or amines, or by means of PCl.sub.5 or POCl.sub.3, have only given brown oils and decomposition products.